PREDATION AND PARASITISM IN A TROPICAL HERBIVORE COMMUNITY

1. Crawling predators were excluded from bamboos attacked by three species of chrysomelid leaf miner in two plots of tropical dry forest in Costa Rica. 2. The percentage of predated mines declined from an average of 61% to an average of 29% in plots where crawling predators had been excluded. There were concomitant increases in successful beetle emergence and in the numbers of beetles attacked by parasitoids. 3. The probability of a miner that had escaped predation being attacked by a parasitoid was the same in experimental and control treatments, indicating that the risks of predation and parasitism are statistically independent. 4. The results were consistent across species and plots with the exception of one species in one plot where emergence was lower in the exclusion treatment than in the control because of very severe parasitoid attack. This result is unexplained. 5. Limited observations, and evidence from the type of damage observed on predated mines, suggest that the most important crawling predators are ants.